Photosensitive resin composition of aqueous emulsion type

ABSTRACT

Present invention provides an aqueous emulsion type photosensitive resin composition which forms a cured film significantly superior in water and solvent resistances in comparison with the conventional aqueous emulsion type photosensitive resin compositions. This photosensitive resin composition contains (A) an emulsion of a photosensitive water-insoluble polymer, the emulsion being obtained by reacting (i) an aqueous polymer emulsion whose main ingredient is a water-insoluble polymer and which contains a polymer having a hydroxyl group with (ii) an N-alkylol(meth)acrylamide, (B) a compound having a photoreactive ethylenically unsaturated group, and (C) a photopolymerization initiator.

TECHNICAL FIELD

The present invention relates to a photosensitive resin composition ofaqueous emulsion type.

More particularly, the present invention relates to a photosensitiveresin composition of aqueous emulsion type which are developable withwater or a dilute aqueous alkaline solution and are useful particularlyas photoresist ink for manufacturing printed wiring boards.

Moreover, the present invention relates to a photosensitive resincomposition which has a good sensitivity and a water and solventresistance. The present photosensitive resin composition is useful forscreen printing stencil and photosensitive printing ink. The compositionis also useful for etching resist, plating resist ink and solder resistink for manufacturing printed wiring boards.

BACKGROUND ART

A photoresist ink developable with a dilute aqueous alkaline solutionrequires no use to solvent to develop. Such kind of ink is superior todevelop with industrial safety, and with prevention of environmentalpollution or fire. Therefore, in recent years, they have been often usedin the fields of ink for manufacturing printed wiring boards, ink forcarving gravure rolls, ink for manufacturing color filter pixels,photosensitive composition for manufacturing screen printing stencilsand ink for manufacturing color filter protective coatings. Conventionalphotoresist ink developable with a dilute aqueous alkaline solutionincludes a photosensitive resin composition such as those disclosed inJP-A 5-224413 and JP-A 5-241340, for example.

However, the above mentioned photoresist ink developable with a diluteaqueous alkaline solution generally has some ingredients which aredissolved or dispersed in various kinds of organic solvents so that theink of the ingredients is uniformly applied to the surface of asubstrate and then subjected to an exposure and to transfer to the nextdevelopment process. Therefore, it is necessary to vaporize the organicsolvent by predrying before exposure. Thus, the use of an organicsolvent causes a problem of industrial safety, environmental pollution,fire control and so on, which is remained unsettled in the process offorming a predried film after its application to a substrate.

Accordingly, there is an object of the present invention to be solved toprovide a photosensitive resin composition of aqueous emulsion typewhich can reduce a problem relating to industrial safety, environmentalpollution, fire control and so on accompanied by use of an organicsolvent in the process of forming a predried film after its applicationto a substrate. The photosensitive resin composition according to thepresent invention is useful as a photoresist ink for manufacturingprinted wiring boards such as etching resist ink, plating resist ink,solder resist ink and marking ink, a photoresist ink for carving gravurerolls, an ink for manufacturing color filter pixels, a photosensitivecomposition for manufacturing screen printing stencils, an ink formanufacturing color filter protective coatings and so on and isdevelopable with water or a dilute aqueous alkaline solution.

Furthermore, there has been known a photosensitive resin composition ofaqueous emulsion type used widely for manufacturing a screen printingstencil.

Such a known photosensitive resin composition for manufacturing a screenprinting stencil includes a composition comprising a diazo resin asphotocrosslinking agent, polyvinyl alcohol, a polyvinyl acetate emulsionand so on (see JP-A 53-51004), a composition comprising a water-solublephotosensitive polymer obtained by adding N-methylol(meth)acrylamide topolyvinyl alcohol (see JP-B 49-5923), a composition obtained,by addingan ethylenically unsaturated compound and a photopolymerizationinitiator to an emulsion of polyvinyl alcohol or polyvinyl acetatehaving styrylpyridinium or styrylquinolinium group (see JP-A 60-10245).

The above mentioned photosensitive resin composition of aqueous emulsiontype for screen printing may be changed into a cured film having acertain water resistance or a solvent resistance. However, in order toproduce a screen printing stencil with greater durability, it isdemanded that a photosensitive resin composition can be changed into acured film having greater water resistance and greater solventresistance.

Accordingly, there is another object to the present invention to besolved to provide a novel photosensitive resin composition of aqueousemulsion type capable of forming a cured film having extremely excellentwater and solvent resistances in comparison with conventionalphotosensitive resin compositions of aqueous emulsion type.

SUMMARY OF THE INVENTION

The above mentioned objects are solved to provide an aqueous emulsiontype photosensitive resin composition comprising:

(A) an emulsion of a photosensitive water-insoluble polymer, theemulsion being obtained by reacting (i) an aqueous polymer emulsionwhich contains a water-insoluble polymer as its main component and whichcontains a polymer having a hydroxyl group with (ii) anN-alkylol(meth)acrylamide;

(B) a compound having a photoreactive ethylenically unsaturated group;and

(C) a photopolymerization initiator.

In this specification, “(meth)acrylic-” means “acrylic-” and/or“methacrylic-”. For example, (meth)acrylic acid means acrylic acidand/or methacrylic acid, and (meth)acrylamide means acrylamide and/ormethacrylamide.

PREFERRED EMBODIMENT OF THE INVENTION

The following is a more detailed explanation on ingredients contained inthe present invention, and preferred embodiment of the presentinvention.

Ingredient (A)

Ingredient (A) is a photosensitive water-insoluble polymer emulsion. Theemulsion is obtained by reacting (i) an aqueous polymer emulsion whichcontains a water-insoluble polymer as its main component and whichcontains a polymer having a hydroxyl group with (ii) anN-alkylol(meth)acrylamide.

The aqueous polymer emulsion (i) in the above mentioned ingredient (A)may be of one kind of polymer or two or more kinds of polymers. Thisaqueous polymer emulsion comprises a water-insoluble polymer as its maincomponent. Furthermore, at least one polymer contained in this aqueouspolymer emulsion has a hydroxyl group. The polymer having a hydroxylgroup may be either a water-soluble polymer or a water-insolublepolymer.

The polymer having a hydroxyl group is only required to be contained inat least a part of the aqueous polymer emulsion. Accordingly, when theaqueous polymer emulsion is only of a water-insoluble polymer, hydroxylgroups must be attached to the water-insoluble polymer. On the otherhand, in case where the aqueous polymer emulsion is of a mixture of awater-insoluble and a water-soluble polymers, the hydroxyl group may beattached to either of the polymers.

Typical aqueous polymer emulsions contain both a protective colloid of apolymer having a hydroxyl group and a water-insoluble polymer.

Illustrative monomer components for obtaining a water-insoluble polymerwithout having a hydroxyl group may include styrene,(meth)acrylonitrile, vinyl acetate, vinyl chloride, unsaturatedpolybasic acids (for example, itaconic acid, maleic anhydride and thelike), α-olefins (for example, isobutene and the like), dienes (forexample, butadiene and the like), acrylic acids (for example, acrylicacid, methacrylic acid and the like), vinyl ethers (for example, ethylvinyl ether and the like), acrylic esters (for example, butyl acrylate,hydroxypropyl acrylate and the like), methacrylic esters (for example,methyl methacrylate, β-hydroxyethyl methacrylate and the like) and(meth)acrylamides (for example, methacrylamide and diacetone acrylamideand the like). Each of the monomers may be polymerized alone or incombination, to obtain a water-insoluble polymer without having ahydroxyl group.

Also, illustrative monomer components for obtaining a water-insolublepolymer having a hydroxyl group may include partially saponified vinylacetate and hydroxyl group-containing (meth)acrylates such as2-hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate,hydroxypropyl (meth)acrylate and polypropylene polyethylene glycolmono(meth)acrylate. Each of the monomers may be polymerized alone, incombination with another monomer, or in combination with a monomer forproducing the aforesaid water-insoluble polymer without a hydroxylgroup, to thereby obtain a water-insoluble polymer having a hydroxylgroup.

Thusly obtained water-insoluble polymer is used to produce the aqueouspolymer emulsion of the present invention, for example, by using aprotective colloid, but not to be limited. Such a protective colloid mayinclude cellulose derivatives such as carboxymethyl cellulose,hydroxypropylmethyl cellulose, hydroxyethyl cellulose and hydroxypropylcellulose; sodium alginate and its derivatives; polyvinyl alcohol basedpolymers such as polyvinyl alcohols obtained by complete or partialsaponification of polyvinyl acetate; water-soluble polyvinyl alcoholderivatives obtained by reacting an acid anhydride-containing compound,carboxyl group-containing compound, epoxy group-containing compound oraldehyde group-containing compound, and the like with an —OH or —OCOCH₃group of polyvinyl alcohol based polymer such as polyvinyl alcoholobtained by partially or completely saponifying polyvinyl acetate and acompletely or partially saponified polyvinyl alcohol, and polyvinylalcohol based copolymers having a vinyl alcohol unit which is obtainedby partially or completely saponifying a polyvinyl acetate portion,using (meth)acrylic acid, (meth)acrylamide, N-methylol(meth)acrylamide,styrene, ethylene, propylene, maleic anhydride, (meth)acrylonitrile,(meth)acrylates as a copolymer component of vinyl acetate.

Among these protective colloids, polyvinyl alcohol, water-solublepolyvinyl alcohol derivative, vinyl alcohol based copolymer having avinyl alcohol unit obtained by partially or completely saponifyingpolyvinyl acetate portion are particularly preferred because they have ahydroxyl group and each of the resulting water-insoluble polymersexhibits good dispersibility.

In the case of using such a protective colloid, the water-insolublepolymer emulsion as the ingredient (i) may be obtained by subjecting amonomer component for producing a water-insoluble polymer to emulsion orsuspension polymerization in a system containing the protective colloid,or by first of all preparing a water-insoluble polymer and thendispersing with the protective colloid.

In case of using a protective colloid, the amount of the protectivecolloid to be incorporated is not particularly limited, but it ispreferably incorporated in an amount of 1-100 parts by weight, morepreferably 5-40 parts by weight, per 100 parts of the solid in thewater-insoluble polymer, which is taken into consideration of thebalance between dispersion stability of the photosensitivewater-insoluble polymer emulsion (A) and water resistance of a curedfilm.

Thusly obtained aqueous polymer emulsion is then reacted withN-alkylol(meth)acrylamide to obtain a photosensitive water-insolublepolymer emulsion as the ingredient (A).

The method for reacting the hydroxyl group in the water-insolublepolymer emulsion as the ingredient (A) (i) with the alkylol group inN-alkylol(meth)acrylamide as the indredient (A) (ii) is not particularlylimited. The reaction can be easily carried out by conventional methodsof adding an acidic catalyst such as inorganic acid, sulfonic acidderivative and ammonium halide into a water-insoluble polymer emulsionand then heating. Furthermore, it is preferable to use, anN-alkylol(meth)acrylamide, in which. alkylol has 1-5 carbon atoms, andin particular, it is preferable to use an N-methylol(meth)acrylamide,which is available at a relatively low price.

The quantity of the unsaturated double bond introduced byN-alkylol(meth)acrylamide is preferably 0.01-5 moles, more preferably0.1-2 moles, per 1.0 kg of a solid of the photosensitive water-insolublepolymer emulsion (A). In such ranges, the best balance between water andsolvent resistances of a cured film of the photosensitive resincomposition of aqueous emulsion type may be achieved.

Ingredient (B)

The photosensitive resin composition of the present invention contains acompound having a photoreactive ethylenically unsaturated group as theingredient (B). Illustrative compound as the ingredient (B) may beincluded in a compound having at least one photoreactive ethylenicallyunsaturated group such as acryloyl group, methacryloyl group, allylgroup, vinyl ether group, acrylamide group, methacrylamide group and thelike.

The specific compound as the ingredient (B) may include an ethylenicallyunsaturated monomer such as trimethylolpropane tri(meth)acrylate,pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,dipentaerythritol penta(meth)acrylate, dipentaerythritolhexa(meth)acrylate, 1,4-butanediol diacrylate, 1,6-hexanedioldi(meth)acrylate neopentyl glycol di(meth)acrylate, tripropylene glycoldi(meth)acrylate, 2,2-bis[4-((meth)acryloxyethoxy)phenyl]propane,2,2-bis[4-((meth)acryloxydiethoxy)phenyl]propane,2-hydroxy-1,3-di(meth)acryloxypropane, ethylene glycol di(meth)acrylate,diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate,phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate,methoxydiethylene glycol (meth)acrylate, tetrahydrofurfuryl(meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate,1-methoxycyclododecadienyl (meth)acrylate, β-(meth)acryloyloxyethylhydrogen phthalate, β-(meth)acryloyloxyethyl hydrogen succinate,3-chloro-2-hydroxypropyl (meth)acrylate, triallyl isocyanurate,methoxyethyl vinyl ether, tert-butyl vinyl ether, lauryl (meth)acrylate,2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, stearyl(meth)acrylate, benzyl (meth)acrylate, bisphenol A-diepoxyacrylic acidadducts, reaction products of tolylenediisocyanate and 2-hydroxypropyl(meth)acrylate, reaction products of phenyl isocyanurate and2-hydroxyethyl (meth)acrylate, glycol ester of maleic acid,(meth)acrylamide, N-methoxymethyl(meth)acrylamide,N,N-dimethyl(meth)acrylamide, (meth)acryloylmorpholine,N-methylol(meth)acrylamide, hydroxypropyl (meth)acrylate, polyethyleneglycol di(meth)acrylate, methylenebis(meth)acrylamide, 2-hydroxyethyl(meth)acrylate and 2,2-bis[4-methacryloyloxypolyethoxyphenyl]propane. Atleast one compound selected from these compounds having a photoreactiveethylenically unsaturated group may be used.

The photosensitive composition of the present invention may contain (b)a compound having at least one carboxyl group and at least onephotoreactive ethylenically unsaturated group in its molecule as theingredient (B). The carboxyl group in compound (b) may be neutralizedwith an organic basic compound such as alkanolamines, and an inorganicbasic compound such as alkaline metal hydroxides, ammonia and the likeas long as the effect of the present invention is obtained.

By incorporating the compound (b), the etching resistance of a curedfilm can be improved when the composition of the present invention isused as an etching resist ink. Furthermore, the incorporation of asufficient amount of (b) renders the cured film of the photosensitiveresin composition of aqueous emulsion type of the present inventioneasily removable even with an aqueous alkaline solution such as aqueoussolutions of alkaline metal hydroxides. This characteristic is usefulfor reusing a screen printing stencil and final removing of cured filmsof an etching resist ink. In order to impart such a characteristic, itis desirable to incorporate compound (b) such that its amount becomes50-100% by weight relative to the total amount of compound (B).Moreover, in some cases, a cured product of the composition of thepresent invention can be removed with sodium periodate and the like.

This compound (b) is not particularly restricted, but is exemplified bya compound (b1) that is a partially esterified product of a compoundhaving one hydroxyl group and one photoreactive ethylenicallyunsaturated group in its molecule with a polycarboxylic acid and acompound (b2) that is a partially esterified product of a compoundhaving one epoxy group and one ethylenically unsaturated group with apolycarboxylic acid.

The compound (b1) can be obtained, for example, by reacting a compoundhaving one hydroxyl group and one photoreactive ethylenicallyunsaturated group in its molecule with a polycarboxylic anhydride. Thecompound (b2) can be obtained, for example, by reacting a compoundhaving only one epoxy group and only one ethylenically unsaturated groupwith a polycarboxylic acid.

Illustrative compound as mentioned a bove may include2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylphthalicacid, 2-(meth)acryloyloxyethyltetrahydrophthalic acid and2-(meth)acryloyloxyethylhexahydrophthalic acid.

The aforesaid polycarboxylic acid is exemplified by succinic acid,phthalic acid, maleic acid, trimellitic acid, pyromellitic acid,tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid,4-methyltetrahydrophthalic acid, 4-ethyltetrahydrophthalic acid,hexahydrophthalic acid, 3-methylhexahydrophthalic acid,4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid and4-ethylhexahydrophthalic acid. These polycarboxylic acids can be usedalone or in appropriate combination of two or more of them. Furthermore,as a polycarboxylic acid, anhydrides of the above listed polycarboxylicacids can also be used.

The compound having one hydroxyl group and one photoreactiveethylenically unsaturated group in its molecule in the aforesaid (b1)may include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl (meth)acrylate, polyethylene glycol(meth)acrylate, polypropylene glycol mono(meth)acrylate and polybutyleneglycol (meth)acrylate, and polycaprolactone mono(meth)acrylate. Thesecan be used alone or in appropriate combination.

The compound having only one epoxy group and only one ethylenicallyunsaturated group in the aforesaid (b2) may include glycidyl(meth)acrylates such as glycidyl (meth)acrylate and 2-methylglycidyl(meth)acrylate, epoxycyclohexyl derivatives of (meth)acrylic acid suchas (3,4-epoxycyclohexyl)methyl (meth)acrylate. These can be used aloneor in appropriate combination of two or more of them.

Ingredient (C)

Furthermore, the photosensitive resin composition of the presentinvention contains a photopolymerization initiator as ingredient (C).Such an ingredient is exemplified by benzoyl alkyl ether, Michler'sketone, di-tert-butylperoxide, tribromoacetophenone, and in addition,substances that easily generate radicals under light irradiation such asanthraquinone derivatives e.g. tert-butylanthraquinone, thioxanthonederivatives e.g. chlorothioxanthone. Also, a photopolymerizationinitiator for loser radiation may be used. One of these compounds may beused alone or in combination of two or more of them.

Furthermore, these photopolymerization initiators may be used togetherwith known photopolymerization accelerator, sensitizer and the like,such as those of benzoic acid type or tertiary amine type includingethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate,2-dimethylaminoethyl benzoate and the like.

Ingredient (D)

In the case where the photosensitive resin composition of the presentinvention is used as a photoresist ink, it is preferable that a binderresin having a carboxyl group is further added as ingredient (D) to thecomposition. This ingredient (D) exhibits a function of reducingtackiness of the surface of a predried film of the photosensitive resincomposition of aqueous emulsion type of the present invention, therebypreventing the photosensitive resin composition from stain a phototoolartwork or the like, when the phototool artwork or the like is directlyattached as well as when it is used in off-contact mode. The ingredientalso functions to improve adhesion, film strength and the like of aresist to be formed. Of course, the ingredient (D) may be incorporated,in the application other than a photoresist ink, for example in aphotosensitive resin composition for manufacturing screen printingstencils.

To fully exhibit such functions, the amount of the carboxyl groups inthe binder resin as ingredient (D) is preferably within the range of20-300 mgKOH/g, particularly 40-250 mgKOH/g as acid value.

In the above ranges, the photosensitive resin composition of the presentinvention when used as a photosolder resist has an excellent developingproperty with a dilute aqueous alkaline solution in a short time andmakes it possible to form a good resist pattern whose exposed and curedportion shows an excellent resistance to a dilute aqueous alkalinesolution. When the photosensitive resin composition of the presentinvention is used as a photoetching resist ink, a good resistance toetching solution can be achieved.

The binder resin as ingredient (D) can be allowed to be carboxyl groupsneutralized with an organic basic compound such as alkanolamine or aninorganic basic compound such as alkaline metal hydroxide and ammonia aslong as the aim of the present invention are achieved.

The binder resin as ingredient (D) preferably has an average molecularweight in the range of 4000-250000, particularly 4000-150000 inconsideration of the balance between performances such as developingproperty, adhesion of a resist to be formed and strength of a coatingfilm.

Typical examples of such ingredient (D), binder resin, are as follows:

(D1) Copolymers of an ethylenically unsaturated monomer component havingat least one carboxyl group, such as (meth)acrylc acid, cinnamic acid,fumaric acid, itaconic acid, crotonic acid and maleic acid, and anethylenically unsaturated monomer component copolymerizable therewith.

The copolymerizable ethylenically unsaturated monomer component isexemplified by (meth)acrylate type unsaturated monomers [linear,branched or alicyclic (meth)acrylates such as methyl (meth)acrylate,ethyl (meth)acrylate, isobutyl (meth)acrylate and cyclohexyl(meth)acrylate]; ethylene glycol type (meth)acrylates such ashydroxyethyl (meth)acrylate, methoxyethyl (meth)acrylate and ethoxyethyl(meth)acrylate, propylene glycol type (meth) acrylates and butyleneglycol type mono(meth)acrylates; glycerol mono(meth)acrylate and thelike; (meth)acrylamide type unsaturated monomers such as(meth)acrylamide and N-methyl(meth)acrylamide; N-substituted maleimidessuch as N-phenylmaleimide and N-cyclohexylmaleimide; styrene,α-methylstyrene, vinyl ether, vinylpyrrolidone and (meth)acrylonitrile.

(D2) Binder resin having a photopolymerizable unsaturated group and alsohaving a carboxyl group (hereafter referred to as “photosensitive binderresin having a carboxyl group”) is also an example of ingredient (D).

The advantage of using such photosensitive binder resin (D2) having acarboxyl group is that exposure sensitivity is greatly improved and thata resist film formed becomes tougher one and therefore becomes resistantto peeling caused by external forces such as friction and can exhibitsteady performance.

An example of such a photopolymerizable unsaturated group includesphotopolymerizable groups such as a (meth)acryloyl group and a vinylgroup. When a binder resin is caused to have this type of unsaturatedgroup, the quantity of the unsaturated group is preferably about 0.01-10mole/Kg (binder resin), and particularly preferably 0.1-5 mole/Kg. It isdesirable that the acid value and weight average molecular weight mayrange the same as those for binder resins having no photopolymerizableunsaturated group.

An example of a base resin constituting the fundamental backbone of thephotosensitive binder resin (D2) having a carboxyl group includesacrylic resins, styrene-maleic acid resins, epoxy resins, polyesterresins, polyether resins, alkyd resins, fluoro resins, silicone resins,carboxyl-modified cellulose, urethane resins and modified resin composedof two or more of them.

Typical examples of photosensitive binder resin (D2) having a carboxylgroup are as follows:

(D2-1) Photosensitive binder resin having a carboxyl group obtained byadding an ethylenically unsaturated monocarboxylic acid (for example,(meth)acrylic acid) and an unsaturated or saturated polybasic acidanhydride (for example, phthalic anhydride and tetrahydrophthalicanhydride) to a polyfunctional epoxy compound having at least two epoxygroups (for example, novolak type epoxy resin and bisphenol A type epoxyresin).

(D2-2) Photosensitive binder resin having a carboxyl group obtained byreacting a compound having a photoreactive ethylenically unsaturatedgroup and one hydroxyl group in its molecule (for example,2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate) with acopolymer of an unsaturated polybasic acid anhydride (for example,maleic anhydride) and an aromatic hydrocarbon having a vinyl group (forexample, styrene) or vinyl alkyl ether.

(D2-3) Photosensitive binder resin having a carboxyl group obtained byreacting some of the carboxyl groups in the copolymer composed of anethylenically unsaturated monomer having no carboxyl group (for example,alkyl (meth)acrylate, hydroxyethyl (meth)acrylate and styrene) and anethylenically unsaturated monomer having a carboxyl group (for example,(meth)acrylic acid, maleic acid, crotonic acid and itaconic acid) withan ethylenically unsaturated compound having only one epoxy group (forexample, glycidyl (meth)acrylate and (3,4-epoxycyclohexyl)methyl(meth)acrylate).

(D2-4) Photosensitive binder resin having a carboxyl group obtained byreacting an ethylenically unsaturated monocarboxylic acid (for example,(meth)acrylic acid) and a saturated or unsaturated polybasic acidanhydride (for example, phthalic acid and tetrahydrophthalic anhydride)to a polymer or copolymer containing an ethylenically unsaturatedmonomer having an epoxy group (for example, glycidyl (meth)acrylate and(3,4-epoxycyclohexyl)methyl (meth)acrylate) as a polymerized unit.

(D2-5) Photosensitive binder resin having a carboxyl group obtained byreacting some of the carboxyl groups of a cellulose derivative having acarboxyl group (for example, hydroxypropylmethylcellulose phthalate andhydroxypropylmethylcellulose acetate succinate) with an ethylenicallyunsaturated compound having only one epoxy group (for example, glycidyl(meth)acrylate and (3,4-epoxycyclohexyl)methyl (meth)acrylate).

(D2-6) Photosensitive binder resin having a carboxyl group obtained byreacting an ethylenically unsaturated compound having only one epoxygroup (for example, glycidyl (meth)acrylate and(3,4-epoxycyclohexyl)methyl (meth)acrylate) to a cellulose derivativehaving a carboxyl group (for example, hydroxypropylmethylcellulosephthalate and hydroxypropylmethylcellulose acetate succinate) and thenfurther reacting a saturated or unsaturated polybasic acid anhydride(for example, phthalic acid and tetrahydrophthalic anhydride).

One kind or two or more kinds of the aforementioned binder resin asingredient (D), is/are selected and incorporated, forming thephotosensitive resin composition of the present invention.

By containing a binder resin having a carboxyl group as ingredient (D),a photoresist ink or a photo sensitive resin composition formanufacturing screen printing stencils made up of a photosensitive resincomposition of the present invention may provide a cured film excellentin film strength and in resistance to a dilute aqueous alkaline solutionwith more stability and also may provide a cured film having highsensitivity and excellent water resistance and excellent solventresistance. Therefore, the photoresist ink or photosensitive resincomposition can yield a screen printing stencil with durability, and isdesirable as a photoresist ink for manufacturing printed wiring boards,such as etching resist ink, plating resist ink, solder resist ink andmarking ink, a photoresist ink for carving gravure rolls, an ink formanufacturing color filter pixels and an ink for manufacturing colorfilter protective coatings.

Ingredient (E)

When the photosensitive resin composition is used as a photoresist ink,an epoxy compound having two or more epoxy groups per molecule mayfurther be incorporated optionally as ingredient (E). Of course, thisepoxy compound may be added for applications other than the photoresistink.

The incorporation of ingredient (E) can make a cured film formed afterexposure and development have improved chemical resistance, solventresistance, acid resistance and electrical corrosion resistance and havehigh hardness through post-baking. This characteristic is particularlyuseful especially in the case of using the composition of the presentinvention as an ink for forming a permanent film such as photosolderresist ink, ink for manufacturing color filter pixels and ink formanufacturing color filter protective coatings.

The aforesaid ingredient (E) is exemplified by an epoxy compoundslightly soluble in a solvent, a general purpose epoxy compound solublein a solvent, and the like. Their specific examples may include phenolnovolak-type epoxy resin, cresol novolak-type epoxy resin, bisphenolA-type epoxy resin, bisphenol A-novolak-type epoxy resin, bisphenolF-type epoxy resin, triglycidyl isocyanurate, “YX 4000” manufactured byYuka-Shell Epoxy Co., Ltd., sorbitol polyglycidyl ether, N-glycidyl-typeepoxy resin, alicyclic-type epoxy resin (e.g., “EHPE-3150” manufacturedby Daicel Chemical Industries, Ltd.), polyol polyglycidyl ethercompounds, glycidyl ester compounds, N-glycidyl-type epoxy resin,tris(hydroxyphenyl)methane-based polyfunctional epoxy resin (e.g.,“EPPN-502H” manufactured by NIPPON KAYAKU Co., Ltd., “TACTIX-742” and“XD-9053” manufactured by Dow Chemical Co., Ltd.), hydrogenatedbisphenol A-type epoxy resin and vinyl-polymerized polymers having anepoxy group such as dicyclopentadiene-phenol-type epoxy resin,naphthalene-type epoxy resin and polyglycidyl (meth)acrylate. These maybe used alone or in combination. Particularly preferred are triglycidylisocyanurate, “YX 4000” manufactured by Yuka-Shell Epoxy Co., Ltd.,phenol novolak-type epoxy resin, cresol novolak-type epoxy resin,bisphenol A-type epoxy resin, bisphenol A-novolak-type epoxy resin, andthe like. Ingredient (E) may be emulsified and dispersed in advance inthe form of an aqueous liquid and may, alternatively, be ofself-emulsifying type. When such ingredient (E) is incorporated, onekind or two or more kinds thereof can be selected and used.

Ingredient (F)

Furthermore, for the purpose, for example, of improvement of storagestability and adjustment of exposure sensitivity of the photosensitiveresin composition of aqueous emulsion type, a water-solublephotosensitive resin, such as polyvinyl alcohol type polymers having astyrylpyridinium or styrylquinolinium group and polyvinyl alcohol-basedpolymers to which N-methylol(meth)acrylamide has been added, may beadded to the photosensitive resin composition of the present invention.

Moreover, additives conventionally used for photosensitive resincompositions such as photoresist may be optionally added to thephotosensitive resin composition of the present invention. Suchadditives include wax emulsions; solvents such as organic ones which areadded in a small amount to achieve a reduction of problems of industrialsafety and health, environmental pollution, fire control and the like,which is a goal of the present invention, (for example, solvents easilysoluble in water, such as alcohols and Cellosolve, and organic solventsslightly soluble or insoluble in water such as acetates and aromatichydrocarbons); leveling agents such as silicone, (meth)acrylatecopolymers and fluorine-type surfactants; polymerization inhibitors suchas hydroquinone, hydroquinone monomethyl ether, pyrogallol,tert-butylcatechol and phenothiazine; halation repellants, defoamers andantioxidants; fibers or powders of glass or metal, which are used as afiller; silica, alumina white, clay, talc, barium carbonate and bariumsulfate which are used as an extender; zinc white, white lead, chromeyellow, minium, ultramarine blue, iron blue, titanium oxide, zincchromate, iron oxide red and carbon black, which are used as aninorganic coloring pigment; Brilliant Carmine 6B, Permanent Red R,Benzidine Yellow, Lake Red C and Phthalocyanine Blue, which are used asan organic coloring pigment; leuko chromophoric dyes; fading monoazodisperse dyes such as UV Blue 236 and POLYESTER BLUE GL-SF; variousadditives such as dyes, natural or synthesized rubber powder, andsurfactants or macromolecule dispersants for improving dispersionstability.

Incorporating Amount

An incorporating amount of each ingredient is not particularly limitedand each of the ingredients may be incorporated in an appropriateproportion depending upon application. The followings are examples ofpreferable proportion of each ingredient in a photoresist ink and aphotosensitive resin composition for manufacturing screen printingstencils.

In the Case of Use as a Photoresist Ink

The incorporating amount of ingredient (B) is preferably 0.1-1000 partsby weight, particularly 1-500 parts by weight, per 100 parts by weightof a solid in ingredient (A). The most suitable amount is 10-300 partsby weight. In such ranges, a cured film obtained from the photosensitiveresin composition of aqueous emulsion type has excellent water andsolvent resistances.

The incorporating amount of ingredient (C) is preferably 0.1-50 parts byweight, particularly 3-30 parts by weight, per 100 parts by weight ofthe total amount of ingredients (B) and (D) and a solid in ingredient(A). The most suitable amount is 0.5-20 parts by weight. In such ranges,the photosensitive resin composition of aqueous emulsion type issuperior especially in exposure sensitivity and cured film therefrom hassufficient water and solvent resistances.

When ingredient (D) is incorporated, the incorporating amount thereof ispreferably 10-1000 parts by weight, particularly 10-500 parts by weight,per 100 parts by weight of a solid in ingredient (A). The most suitableamount is 50-300 parts by weight. In such ranges, the photosensitiveresin composition of aqueous emulsion type is excellent in exposuresensitivity and developability with a dilute aqueous alkaline solution,and a cured film formed therefrom is free from the inconvenience of itsbrittleness, cracking or peeling. The cured film can be improved in itshardness enough to become excellent in water resistance and solventresistance. Moreover, the cured film after predrying has a low tackinessso that the photosensitive resin composition is suitable for theso-called on-contact exposure using a phototool artwork. Furthermore,when the photosensitive resin composition of the present invention isused as a photoetching resist ink, it becomes excellent in resistance toan etching solution.

When ingredient (E) is incorporated, its incorporating amount ispreferably 1-500 parts by weight, particularly 10-300 parts by weight,per 100 parts by weight of the total amount of ingredients (B) and (D)and a solid in ingredient (A). The most suitable amount is 10-100 partsby weight. In such ranges, a strong film particularly excellent inchemical resistance, solvent resistance and acid resistance is formedvia post-baking. In addition, no reaction of curing of ingredient (E),the epoxy compound, occurs during the predrying, thereby ensuring a widedeveloping range, which means a range of predrying conditions underwhich developability is maintained or a range in which no thermal fogoccurs and which is also called as “” predrying control range” or“predrying allowable range”.

When the photosensitive resin composition of the present invention isused as a solder resist ink, the aforesaid ranges are most suitablesince a solder resist can be obtained that has particularly highstrength and has excellent electrical corrosion resistance and goldplating resistance.

In the case of use as a photosensitive resin composition formanufacturing screen printing stencils.

The incorporation ratio of ingredient (A) to ingredient (B) in weightratio of active components is preferably 100:10-1000, and particularly100:20-500. In such ranges, a cured film obtained from thephotosensitive resin composition of aqueous emulsion type becomes tohave excellent water resistance and solvent resistance. By the “activecomponent” used herein is meant a solid or a material that will become asolid during the cured film formation.

The incorporation ratio of ingredient (C) to ingredient (B) in weightratio of active components is preferably 100:0.1-50, and particularly100:0.3-30. In such ranges, a cured film obtained from thephotosensitive resin composition of aqueous emulsion type becomes tohave excellent water resistance and solvent resistance.

When a powdered inactive solid is incorporated, it is desirable toincorporate the powdered inactive solid in 1-60 parts by weight,particularly 5-50 parts by weight per 100 parts by weight of the activecomponent of the photosensitive resin composition of the presentinvention. When the amount of the powdered inactive solid is in suchranges, a cured film obtained from the photosensitive resin compositionof the present invention is free from the inconvenience of itsbrittleness, cracking or peeling. The cured film can be improved in itshardness enough to become excellent in water resistance and solventresistance.

Applications

The photosensitive resin composition of the present invention ispreferably used as a photoresist ink or a photosensitive resincomposition for manufacturing screen printing stencils. It can also beparticularly suitably used as photoresist inks for manufacturing printedwiring boards such as an etching resist ink, plating resist ink, solderresist ink and marking ink, an ink for manufacturing color filter pixelsand an ink for manufacturing color filter protective coatings. It may beused as a photosensitive resin composition for manufacturing screenprinting stencils or a photoresist ink for carving gravure rolls.Furthermore, the photosensitive resin composition of the presentinvention can be used as the so-called dry film resist by applying itonto a support film such as a polyester film to form a film.

An example of the applications of the photosensitive resin compositionof the present invention is a printed wiring board obtained by thefollowing process. After applying a photosensitive resin compositiononto a substrate on whose surface a metallic layer has been disposed anddrying it, a predetermined part of the photosensitive resin compositionis selectively exposed to form a cured film. The remaining non-exposedpart of the photosensitive resin composition is washed away. Theresulting substrate is immersed in an etching solution to subject a partof the metallic layer to etching treatment. The cured film is thereafterremoved to yield a printed wiring board.

The cured film made up of the photosensitive resin composition of thepresent invention is used as an etching resist as described supra.Furthermore, it may be used as a cured film as it is (for example, asolder resist). In this case, the cured film remains on an end product,a printed wiring board as a permanent coating film never peeled off.

When a cured film is used as a permanent protective coating describedabove, a cured film formed via exposure and development can bepost-baked by use of hot air heating, electromagnetic induction heating,hot press, far infrared radiation drying or the like, or be post-UVcured with ultraviolet irradiation to be improved in its strength,hardness, chemical resistance and so on, which are particularlyimportant as physical properties of permanent protective coatings.

In these cases, the substrate on which a cured film is to be formed maybe one having a conductive circuit on its surface.

How to Use

The photosensitive resin composition of the present invention can beused by methods heretofore known.

The following is an example of how to use a photosensitive resincomposition for manufacturing screen printing stencils of the presentinvention.

Direct method: A method wherein, for example, a screen printing stencilwith a cured film having a thickness of 1-10000 μm is obtained byapplying a photosensitive resin composition onto a screen made ofsynthetic resin such as polyester, nylon and polyethylene, syntheticresin with metal, such as nickel, deposited thereon, or stainless steel,drying, selectively exposing and then developing.

Direct-indirect method: A method wherein a screen printing stencil is.obtained by the following process. A photosensitive resin composition isapplied onto a releasable film such as those of polyethylene, polyvinylchloride and polyester and then dried, yielding, for example, a filmwith a photosensitive layer having a thickness of 10-500 μm. Using thisfilm, the photosensitive layer is transferred to a screen by applying inadvance, or while applying, water, a photosensitive resin composition orthe like, and thereafter is exposed and developed to form the screenprinting stencil. This method includes simpler operations than thedirect method including repetitive application of the same or similarphotosensitive material onto a screen. It can also produce stencilssuperior in printing characteristics to those by the direct method.

Indirect method: A method wherein a screen printing stencil is obtainedby selectively exposing a filmized photosensitive resin composition lefton a releasable film on which the photosensitive resin was filmized,developing, and then transferring to a screen.

The photosensitive resin composition of aqueous emulsion type accordingto the present invention has high sensitivity and can form a cured filmexcellent especially in water resistance and solvent resistance. Thus,it can produce screen printing stencils of excellent durability.

Because of such characteristics, the photosensitive resin composition ofthe present invention is suitably used for manufacturing screen printingstencils of great thickness as well as those of ordinary thickness (the“thickness” used herein means the thickness a cured film and excludesthe thickness of ascreen mesh itself.) There is noclear definition forthe “great thickness”, but it is defined to be a thickness of not lessthan 100 μm for a cured film formed on ascreen. The “ordinary thickness”is defined to be a thickness less than 100 μm.

The following description is made, as an example, on the manufacture ofa screen printing stencil of great thickness by the direct method.

In the direct method, for example, a photosensitive resin composition isapplied onto a screen with a bucket for great thickness and dried(particularly in the case of very great thickness, the applying anddrying steps may be repeated twice or more to achieve a predeterminedthickness), followed by exposure and development, thereby yielding adesired screen printing stencil of great thickness.

However, in the case of using a conventional composition obtained byincorporating a diazo resin as photocrosslinking agent to a mixtureincluding polyvinyl alcohol and polyvinyl acetate emulsion using aphotosensitive resin composition comprising a water-solublephotosensitive polymer obtained by adding N-methylol(meth)acrylamide topolyvinyl alcohol, and using a composition obtained by adding anethylenically unsaturated compound and a photopolymerization initiatorto an emulsion of polyvinyl acetate or polyvinyl alcohol having astyrylpyridinium or styrylquinolinium group, a cured film of greatthickness has an insufficient exposure sensitivity or needs an excesslong time exposure, and also tends to result in incomplete cure at thedeep portion in the film.

Therefore, there are the following problems with the above conventionalcompositions. It is difficult to manufacture printing stencils becauseof poor image formation, poor developing property, a cured film's poorwater resistance, poor solvent resistance, poor adhesion to a screensubstrate, poor strength, or the like. When using a printing ink, anetching resist ink, photosensitive paste, thermosetting paste or thelike, the screen printing stencil may have insufficient durability orthe printed pattern may lack minuteness. For such reasons, if a filmformed on a screen has a thickness of 400 μm or more, it is difficult tomanufacture high-performance screen printing stencils. On the otherhand, in the photosensitive resin composition of the present invention,even when a film has a great thickness, it has a high exposuresensitivity and requires a short exposure time. It is fully cured at itsdeep portion. The resulting cured film is excellent in water resistance,solvent resistance, adhesion to a screen substrate and strength.

Accordingly, although the photosensitive resin composition of thepresent invention has no upper limit for its thickness, it shows goodproperties as a screen printing stencil of great thickness when thethickness of a film formed on a screen mesh ranges from 100 to 10000 μm.A preferable range is 100-5000 μm. When the thickness falls within therange of 100-3000 μm, the optimum properties are obtained. In otherwords, the photosensitive resin composition of the present inventionshows good image formability and good developing property and its curedfilm is excellent in water resistance and solvent resistance in spite ofits great thickness. Therefore, even in a long time use, the durabilityof a screen printing stencil and minuteness of the printed pattern aremaintained. Furthermore, when the film thickness falls within theaforesaid ranges provided that their lower limits are 400 μm, thephotosensitive resin composition of the present invention exhibits greatadvantage beyond that of the conventional products.

EXAMPLES

The present invention will be explained with reference to the followingexamples about (I) a photoresist ink and (II) a photosensitive resincomposition for manufacturing a screen print stencil. However, thepresent invention is not limited to these examples.

All the units “parts” and “%” used hereafter mean “parts by weight” and“wt %”, respectively, unless otherwise stated.

In addition, “weight average molecular weight” was measured by GPC (GelPermeation Chromatography) under the following measuring conditions.

GPC Measuring Condition

In the measurement, a THF (tetrahydrofuran) solution was prepared whoseconcentration of the solid of each sample was 10 mg/ml, and themeasurement was carried out with the injection amount of 100 μl.

Measuring Conditions

GPC Measuring Apparatus:“SHODEX SYSTEM 11” manufactured by Showa DenkoK. K.

Column: “SHODEX KF-800P”, “SHODEX KF-805”, “SHODEX KF-803” and “SHODEXKF-801” in series, manufactured by Showa Denko K. K.

Transfer Layer: THF

Flow Rate: 1 ml/min

Column Temperature: 45° C.

Detector: RI

Conversion: Polystyrene

Synthesis Example 1 Synthesis of Ingredient (A)

Into a glass vessel equipped with a reflux cooling tube, a droppingfunnel, a thermometer, a nitrogen inlet and a stirrer, 10 g of PVA-217(polyvinyl alcohol manufactured by Kuraray Co., Ltd., degree ofpolymerization: 1700, degree of saponification: 88 mole %) and 90 g ofion-exchange water were charged and dissolved on heating, followed byadjusting to pH4.0. Subsequently, 5 g of methyl methacrylate, 5 g ofn-butyl acrylate and 0.02 g of n-dodecylmercaptan were added whilestirring at 150 rpm. After fully replacing with nitrogen, thetemperature was elevated to 80° C. Then a 1% ammonium persulfatesolution was dropped to initiate polymerization, followed by thedropping of a mixture of 45 g of methyl methacrylate, 25 g of n-butylacrylate, 20 g of isobutyl methacrylate and 0.18 g of n-dodecylmercaptanfor 2 hours accompanying the dropping of 10 g of a 1% ammoniumpersulfate solution for 2 hours. Subsequently, an aging at thattemperature for 3 hours resulted in an emulsion of a water-insolublepolymer having a hydroxyl group. To this emulsion was dissolved 5 g ofN-methylolacrylamide and then were added 2 g of a 0.1% aqueousmethoxyhydroquinone solution and 4 g of 5% phosphoric acid.Subsequently, the mixture was allowed to react at 80° C. for 5 hours.

After the completion of the reaction, the reaction mixture wasneutralized with an aqueous sodium hydroxide solution, followed bydilution with ion-exchange water, resulting in an emulsion (A-1) of aphotosensitive water-insoluble polymer with a 30% solid.

Synthesis Example 2 Synthesis of Ingredient (A)

Into a glass vessel equipped with a reflux cooling tube, a droppingfunnel, a thermometer, a nitrogen inlet and a stirrer, 10 g of PVA-224(polyvinyl alcohol manufactured by Kuraray Co., Ltd., degree ofpolymerization: 2400, degree of saponification: 88 mole %) and 90 g ofion-exchange water were charged and dissolved on heating, followed byadjusting to pH4.0. Subsequently, 5 g of methyl methacrylate, 5 g ofn-butyl acrylate and 0.02 g of n-dodecylmercaptan were added whilestirring at 150 rpm. After fully replacing with nitrogen, thetemperature was elevated to 80° C. Then a 1% ammonium persulfatesolution was dropped to initiate polymerization, followed by thedropping of a mixture of 50 g of methyl methacrylate, 20 g ofhydroxyethyl methacrylate, 20 g of n-butyl acrylate and 0.18 g ofn-dodecylmercaptan for 2 hours accompanying the dropping of 10 g of a 1%ammonium persulfate solution for 2 hours. Subsequently an aging at thattemperature for 3 hours resulted in an emulsion of a water-insolublepolymer having a hydroxyl group. To this emulsion was dissolved 5 g ofN-methylolacrylamide and then were added 2 g of a 0.1% aqueousmethoxyhydroquinone solution and 4 g of 5% phosphoric acid.Subsequently, the mixture was allowed to react at 80° C. for 5 hours.

After the completion of the reaction, the reaction mixture wasneutralized with an aqueous sodium hydroxide solution, followed bydilution with ion-exchange water, resulting in an emulsion (A-2) of aphotosensitive water-insoluble polymer with a 30% solid.

Synthesis Example 3 Synthesis of Ingredient (D)

Into a four-necked flask equipped with a reflux cooling tube, athermometer, a glass tube for nitrogen replacement and a stirrer, 20parts of methacrylic acid, 80 parts of methyl methacrylate, 100 parts ofmethyl ethyl ketone and 1 part of azobisisobutyronitrile were added andthen allowed to polymerize at 75° C. for 5 hours on heating under anitrogen flow, resulting in a 50% solution (P-1) of carboxylgroup-containing binder resin (a solution of an acrylic ester typecopolymer corresponding to a binder resin having a carboxyl group (D1)).The resulting binder resin had a weight average molecular weight of110000 and an acid value of 130 mgKOH/g.

Synthesis Example 4 Synthesis of Ingredient (D)

214 parts of a cresol novolak type epoxy resin (the trade name: EPICLONN-680, manufactured by Dainippon Ink and Chemicals Inc., epoxyequivalents: 214) was dissolved under heating in 60 parts of methylethyl ketone to obtain a mixture. Then, 74 parts of acrylic acid, 0.1part of hydroquinone and 2.0 parts of dimethylbenzylamine were added tothe mixture while blowing the air under stirring, and allowed to reactat 80° C. for 24 hours in an ordinary manner. After cooling theresulting reaction solution, 136 parts of methyl ethyl ketone and 76parts of tetrahydrophthalic anhydride were added thereto. The mixturewas heated to 80° C. to react for about 10 hours under stirring,producing a 65% solution (P-2) of a photosensitive binder resin having acarboxyl group, the solution corresponding to a solution of aphotosensitive binder resin (D2-1) having a carboxyl group. Theresulting binder resin had a weight average molecular weight of 12000and an acid value of 77 mgKOHg.

Synthesis Example 5 Synthesis of Ingredient (D)

150 parts of a styrene-maleic anhydride copolymer (the trade name:SMA-1000A, manufactured by Elfatochem, Inc.) was dissolved under heatingin 143 parts of methyl ethyl ketone to obtain a mixture. Then, 61 partsof 2-hydroxyethyl acrylate, 0.1 part of hydroquinone and 3.0 parts ofdimethylbenzylamine were added to the mixture while blowing the airunder stirring, and allowed to react at 80° C. for 12 hours in anordinary manner. To the resulting reaction solution, 28 parts ofn-butanol was further added and allowed to react for additional about 24hours, producing a 60% solution (P-3) of a photosensitive binder resinhaving a carboxyl group, the solution corresponding to a solution of aphotosensitive binder resin (D2-2) having a carboxyl group. Theresulting binder resin had a weight average molecular weight of 7500 andan acid value of 156 mgKOH/g.

Synthesis Example 6 Synthesis of Ingredient (D)

Into a four-necked flask equipped with a reflux cooling tube, athermometer, a glass tube for nitrogen replacement and a stirrer, 20parts of methacrylic acid, 80 parts of methyl methacrylate, 100 parts ofmethyl ethyl ketone, 0.5 parts of laurylmercaptan and 4 parts ofazobisisobutyronitrile were added and then allowed to polymerize at 75°C. for 5 hours on heating under a nitrogen flow, resulting in a 50%copolymer solution.

To the above 50% copolymer solution were added 0.05 parts ofhydroquinone, 15 parts of glycidyl methacrylate and 2.0 parts ofdimethylbenzylamine, and then addition polymerization was conducted at80° C. for 24 hours while blowing the air. Subsequently, 13 parts ofmethyl ethyl ketone was added to produce a 50% solution (P-4) of aphotosensitive binder resin having a carboxyl group, the solutioncorresponding to a solution of a photosensitive binder resin (D2-3)having a carboxyl group. The resulting binder resin had a weight averagemolecular weight of 15000 and an acid value of 62 mgKOH/g.

Synthesis Example 7 Synthesis of Ingredient (D)

Into a four-necked flask equipped with a reflux cooling tube, athermometer, a glass tube for nitrogen replacement and a stirrer, 70parts of glycidyl methacrylate, 10 parts of methyl methacrylate, 20parts of tert-butyl methacrylate, 100 parts of methyl ethyl ketone, 0.5part of laurylmercaptan and 3 parts of azobisisobutyronitrile were addedand then allowed to polymerize at 75° C. for 5 hours on heating under anitrogen flow, resulting in a 50% copolymer solution.

To the above 50% copolymer solution were added 0.05 part ofhydroquinone, 37 parts of acrylic acid and 2.0 parts ofdimethylbenzylamine, and then addition polymerization was conducted at80° C. for 24 hours while blowing the air. Subsequently, 38 parts oftetrahydrophthalic anhydride and 73 parts of methyl ethyl ketone wereadded and allowed to react at 80° C. for 10 hours to produce a 50%solution (P-5) of a photosensitive binder resin having a carboxyl group,the solution corresponding to a solution of a photosensitive binderresin (D2-4) having a carboxyl group.

The resulting binder resin had a weight average molecular weight of22000 and an acid value of 80 mgKOH/g.

Synthesis Example 8 Synthesis of Ingredient (D)

Into a four-necked flask equipped with a reflux cooling tube, athermometer, a glass tube for nitrogen replacement and a stirrer, 20parts of methacrylic acid, 80 parts of methyl methacrylate, 100 parts ofpropylene glycol monomethyl ether acetate and 0.5 parts ofazobisisobutyronitrile were added and then allowed to polymerize at 75°C. for 5 hours on heating under a nitrogen flow, thereby resulting in a50% solution (P′-1) of carboxyl group-containing binder resin (asolution of an acrylic ester type copolymer corresponding to a binderresin having a carboxyl group (D1)). The resulting binder resin had aweight average molecular weight of 90000 and an acid value of 130mgKOH/g.

Synthesis Example 9 Synthesis of Ingredient (D)

150 parts of a styrene-maleic anhydride copolymer (the trade name:SMA-1000A, manufactured by Elfatochem, Inc.) was dissolved under heatingin 143 parts of propylene glycol monomethyl ether acetate to obtain amixture. Then, 51 parts of 2-hydroxyethyl acrylate, 0.1 part ofhydroquinone and 3.0 parts of dimethylbenzylamine were added whileblowing the air under stirring, and allowed to react at 80° C. for 12hours in an ordinary manner. To the resulting reaction solution, 28parts of n-butanol was further added and allowed to react for additionalabout 24 hours to produce a 60% solution (P′-2) of a photosensitivebinder resin.

The resulting binder resin had a weight average molecular weight of 7500and an acid value of 156 mgKOH/g.

Synthesis Example 10 Synthesis of Ingredient (D)

Into a four-necked flask equipped with a reflux cooling tube, athermometer, a glass tube for nitrogen replacement and a stirrer, 20parts of methacrylic acid, 80 parts of methyl methacrylate, 100 parts ofpropylene glycol monomethyl ether acetate, 0.5 parts of laurylmercaptanand 2 parts of azobisdimethyvaleronitrile were added and then allowed topolymerize at 110° C. for 5 hours on heating under a nitrogen flow,resulting in a 50% copolymer solution.

To the above 50% copolymer solution were added 0.05 parts ofhydroquinone, 15 parts of glycidyl methacrylate and 2.0 parts ofdimethylbenzylamine, and then addition polymerization was conducted at80° C. for 24 hours while blowing the air. Subsequently, 11 parts ofpropylene glycol monomethyl ether acetate was added to produce a 50%solution (P′-3) of a photosensitive binder resin.

The resulting binder resin had a weight average molecular weight of18000 and an acid value of 62 mgKOH/g.

Reference Production Example 1

In 1000 g of water was dissolved 200 g of partially saponified polyvinylacetate with a degree of saponification of 88% (the trade name: GohsenolGH-17, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.,degree of polymerization: 1700).

In this aqueous solution, 40 g of N-methylol acrylamide was dissolvedand then 2 g of a 0.1% aqueous methoxyhydroquinone solution, 3 g of 8%phosphoric acid was added thereto, followed by a reaction at 60° C. for20 hours. After the completion of the reaction, the resulting mixturewas neutralized with a 5% aqueous sodium hydroxide solution and waterwas added so that the total weight became 1500 g, resulting in a 15%aqueous solution (F-1) of an N-methylol acrylamide adduct of polyvinylalcohol.

Examples I-1 to I-20

As for each of Examples I-1 to I-20, a photosensitive resin compositionof aqueous emulsion type was prepared in the following manner. A mixtureresulting from incorporating the ingredients in a composition given inTable 1 or 2 was stirred to mix. The resulting mixture was fullydispersed with a homomixer and then heated to a liquid temperature of65° C. Finally, organic solvent components were removed under airblowing.

Comparative Examples I-1 to I-6

As for each of Comparative examples I-1 to I-6, a photosensitive resincomposition was prepared in the following manners. A mixture resultingfrom incorporating the ingredients in a composition given in Table 1 or2 was stirred to mix for Comparative examples I-1 to I-3 or was fullykneaded with three rolls for Comparative examples I-4 to I-6.

TABLE 1 Photoetching resist ink Comparative Examples Examples I-1 I-2I-3 I-4 I-5 I-6 I-7 I-8 I-9 I-10 I-1 I-2 I-3 Ingredi- A-1 80 80 80 80 80ent(A) A-2 80 80 80 80 80 Ingredi- P-1 400 400 ent(D) P-2 400 400 P-3330 330 P-4 400 400 P-5 400 400 P¹-1 444 P¹-2 370 P¹-3 370 Ingredi-Dipentaerythritol ent (B) hexaacrylate Aronix M-101^(*1)) 60 60 60 60 6060 60 60 60 60 60 60 60 Aronix M-309^(*2)) 60 60 60 60 60 60 60 60 60 6060 60 60 Ingredi- Irgacure907^(*3)) 30 30 30 30 30 30 30 30 30 30 30 3030 ent (C) 2,4-Diisopropyl- thioxanthone Kayacure DETX 5 5 5 5 5 5 5 5 55 5 5 5 ^(*4)) Ingredi- YX 4000^(*5)) ent (E) Epicron N-680^(*6))Pigment, Silica (Average etc. particle diameter 1 μm) Barium sulfateVictoria Blue 5 5 5 5 5 5 5 5 5 5 5 5 5 BOH^(*7)) Phthalocyanine GreenSolvent Water 330 330 330 330 330 330 330 330 330 330 Carbitol cetate163 235 235 Hydroquinone 2 2 2 2 2 2 2 2 2 2 2 2 2 Dicyandiamide 0.5 0.50.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Modaflow^(*8)) EpoxyMelamine curing agent

TABLE 2 Photosolder resist ink Comparative Examples Examples I-11 I-12I-13 I-14 I-15 I-16 I-17 I-18 I-19 I-20 I-4 I-5 I-6 Ingredi- A-1 120 120120 120 120 ent(A) A-2 120 120 120 120 120 Ingredi- P-1 480 480 ent(D)P-2 480 480 P-3 370 370 P-4 480 480 P-5 480 480 P-1 636 P-2 530 P-3 530Ingredi- Dipentaerythritol 42 42 42 42 42 42 42 42 42 42 42 42 42 ent(B) hexaacrylate Aronix M-101^(*1)) Aronix M-309^(*2)) Ingredi-Irgacure907^(*3)) 36 36 36 36 36 36 36 36 36 36 36 36 36 ent (C)2,4-Diisopropyl- 4 4 4 4 4 4 4 4 4 4 4 4 4 thioxanthone Kayacure DETX^(*4)) Ingredi- YX 4000^(*5)) 80 80 80 80 80 80 80 ent (E) EpicronN-680^(*6)) 100 100 100 100 100 100 Pigment, Silica (Average 84 84 84 8484 84 84 84 84 84 84 84 84 etc. particle diameter 1 μm) Barium sulfate126 126 126 126 126 126 126 126 126 126 126 126 126 Victoria BlueBOH^(*7)) Phthalocyanine 4 4 4 4 4 4 4 4 4 4 4 4 4 Green Solvent Water576 596 576 596 558 578 576 596 576 596 Carbitol cetate 392 498 518Hydroquinone Dicyandiamide Modaflow^(*8)) 8 8 8 Epoxy Melamine 8 8 8 8 88 8 8 8 8 8 8 8 curing agent

In Tables 1 and 2,

1) Phenol-modified monofunctional acrylate manufactured by Toagosei Co.,Ltd.

2) Trimethylolpropane triacrylate manufactured by Toagosei Co., Ltd.

3) Photopolymerization initiator manufactured by Ciba-Geigy Corp.

4) Photopolymerization initiator manufactured by Nippon Kayaku Co., Ltd.

5) Epoxy compound with an epoxy equivalent of 195 manufacture byYuka-Shell Epoxy Co., Ltd.

6) Epoxy resin of cresol novolak type with an epoxy equivalent of 214manufactured by Dainippon Ink &Chemicals, Inc.

7) Organic dye manufactured by Hodogaya Chemical Co., Ltd.

8) Leveling agent manufactured by Monsanto Company

For photosensitive resin compositions of Examples I-1 to I-10 andComparative examples I-1 to I-3, results of evaluation of performance asa photoetching resist ink are shown in Table 3. The evaluation wasconducted by using a resist pattern prepared by the following method.Full screen printing with a photosensitive resin composition was put onan FR-4 double-sided copper clad laminate whose substrate and copperfoil are 1.6 mm and 35 μm in thickness, respectively, and then dried ata temperature of 80° C. for 15 minutes in a hot air convection typedrier, yielding a predried film having a thickness of 10 μm. Thepredried film was exposed at 100 mJ/cm² under tight contact by using aphototool artwork, followed by development with a 1% aqueous sodiumcarbonate solution, yielding the aforesaid resist pattern.

[a. Drying Property]

Tackiness of the surface of a coating film after predrying was evaluatedby touching with fingers. The results are indicated using the followingsymbols:

⊚: The surface had no tackiness.

∘: The surface had a little tackiness.

Δ: The surface had tackiness.

x : The surface had a significant tackiness.

[b. Exposure Sensitivity]

The number of steps of a film applied to a copper glass epoxy substrate,the number being evaluated by using a step tablet No. 2 (21 steps)manufactured by Kodak Co.

[c. Developing Property]

Developing property was evaluated based on visual observation and theresults are indicated by the following symbols:

⊚: The exposed portion with a cured film remains and the non-exposedportion has been removed. No portions were left undeveloped.

∘: A slight indentation was found along the line on the boundary betweenthe non-exposed portion and the exposed portion.

x : Neither the exposed portion nor the non-exposed portion was able tobe removed.

[d. Pencil Hardness]

Pencil hardness was evaluated through the measurement according to JISK5400 by using Mitsubishi Hi-uni (manufactured by Mitsubishi Pencil Co.,Ltd.)

[e. Adhesion]

A resulting cured film was subjected to a self-adhesive cellophane tapepeeling test by cross cutting according to JIS D0202.

[f. Resistance to Etching Solution]

The aforesaid copper clad laminate with a resist pattern was subjectedto etching at 45° C. for 240 seconds in a 40 wt % aqueous ferricchloride solution. Subsequently, the presence of peeling of the curedfilm was observed. When no peeling was observed, it was evaluated as“good”.

[g. Removing Property of Resist]

Removing property of a resist was evaluated through the measurement of atime (in second) needed to completely remove a cured film by spraying a3% aqueous sodium hydroxide solution at 45° C. at a spray pressure of 2kg/cm² to remove a resist away.

For the photosensitive resin compositions of Examples I-11to I-20 andComparative examples I-4 to 6, results of evaluation of performance as aphotosolder resist ink are shown in Table 4. The evaluation wasconducted using a resist pattern prepared by the following method. Fullscreen printing with a photosensitive resin composition was put on anFR-4 double-sided copper clad laminate whose substrate and copper foilare 1.6 mm and 35 μm in thickness, respectively, and then predried at80° C. for 30 minutes, forming a predried film having a thickness of 20μm. The predried film was exposed at 150 mJ/cm² under tight contact byusing a phototool artwork, followed by development with a 1% aqueoussodium carbonate solution and additional post-baking at 150° C. for 30minutes, yielding the aforesaid resist pattern.

Furthermore, (a) drying property, (b) exposure sensitivity, (c)developing property, (d) pencil hardness and (e) adhesion were evaluatedin the same manners as those in Example I-1, but (h) heat resistance insoldering was evaluated in the following manner.

[h. Heat Resistance in Soldering]

After the application of water-soluble flux, the specimen was immersedin a molten solder bath at 260° C. for 15 seconds and then washed withwater. After three times repetition of this cycle, the degree ofdiscoloration of the surface was observed and evaluated as follows:

x : Significant discoloration was found.

∘: Slight discoloration was found.

⊚: No abnormalities were found.

Subsequently, by the self-adhesive cellophane tape peeling test by crosscutting according to JIS D0202, the adhesion of films was evaluated asfollows:

x : Swelling or peeling of a resist occurred before the cross cut test.

∘: The cross cut portion was partially peeled during tape peeling.

⊚: No peeling occurred in the cross cut portion.

TABLE 3 Examples Comparative Examples I-1 I-2 I-3 I-4 I-5 I-6 I-7 I-8I-9 I-10 I-1 I-2 I-3 a. Drying ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ property b.  6 6  6  6  6  6  6  6  6  6  6  6  6 Exposure sensitivity c. ⊚ ⊚ ⊚ ⊚ ⊚ ⊚⊚ ⊚ ⊚ ⊚ ∘ ∘ ∘ Developing property d. Pencil 4H 4H 4H 4H 4H 4H 4H 4H 4H4H 4H 4H 4H hardness e. Adhesion 100/100 100/100 100/100 100/100 100/100100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 f. GoodGood Good Good Good Good Good Good Good Good Good Good Good Resistanceto etching solution g. 46 48 55 57 40 41 51 53 48 49 62 60 68 Removingproperty of resist

TABLE 4 Comparative Examples Examples I-11 I-12 I-13 I-14 I-15 I-16 I-17I-18 I-19 I-20 I-4 I-5 I-6 a. Drying property ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚b. Exposure 8 8 8 8 8 8 8 8 8 8 8 8 8 sensitivity c. Developing ⊚ ⊚ ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ∘ ∘ ∘ property d. Pencil hardness 5H 5H 5H 5H 5H 5H 5H 5H 5H5H 5H 5H 5H e. Adhesion 100/100 100/100 100/100 100/100 100/100 100/100100/100 100/100 100/100 100/100 100/100 100/100 100/100 h. Heat Surface⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ resistance blushing in Adhesion ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ soldering

The above results reveal that since the composition of the presentinvention is an aqueous emulsion, it can produce cured films havingexcellent adhesion, hardness, heat resistance and so on comparable tothose achieved by a diluted alkali-developable ink in organic solventswith reducing a problem of odor, flammability and 80 on.

In other words, the composition of the present invention is aphotosensitive resin composition of aqueous emulsion type that isdevelopable with water or a dilute aqueous alkaline solution. It can beused with great effectiveness as a photoresist ink and the like withoutcausing problems such as industrial safety and health, environmentalpollution and fire control.

Furthermore, although not shown in the form of Examples, thephotosensitive resin composition of aqueous emulsion type according tothe present invention, which is developable with water or a diluteaqueous alkaline solution, is also excellent for use for forming a thickfilm resist, such as thick film plating resist and thick film solderresist, as well as use f or manufacturing screen printing stencils.

Photosensitive Resin Composition (II) for Manufacturing Screen PrintingStencils

Example II-1

15 g of benzoin isobutyl ether, 75 g of pentaerythritol triacrylate and75 g of Aronix M-8030 (polyester acrylate manufactured by Toagosei Co.,Ltd.) were added to 200 g of the photosensitive water-insoluble polymeremulsion (A-1) obtained in Synthetic example 1 under stirring andemulsified. To the emulsion were mixed 90 g of water and 6 g of Blue-FLBconc. (a blue pigment dispersed in water manufactured by DainichiseikaColour & Chemicals Mfg. Co., Ltd.), yielding a photosensitive liquid(sample II-1).

A photosensitive film having a thickness of 80 μm including thethickness of the screen was prepared through three cycles of processcomprising applying the above photosensitive liquid to 225-meshpolyester mesh fabric (yellow) with a bucket and drying it (hot-airdrying at 30-40° C.). The screen photosensitive film was brought intocontact with a positive film for manufacturing a printed wiring and thenexposed to a 3 KW metal halide lamp (manufactured by Ushio Inc.) for 30seconds at a distance of 1 m. Then the mask film was removed, and thenthe resulting specimen was immersed in water at 20° C. for 2 minutes,followed by washing with shower to remove the non-exposed portion. Bydrying the thus developed photosensitized board in the 45° C. hot airfor 15 minutes, a screen stencil with 150 μm wiring for printed wiringwas obtained.

Using this stencil, an etching resist ink (PLAS FINE PER-210Bmanufactured by Goo Chemical Co., Ltd.) was printed on 3000 pieces ofcopper-laminated boards, producing good printed pieces with no failureof image. This reveals that the screen printing stencil obtained in thisExample had excellent durability.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Example II-2

To 200 g of the photosensitive water-insoluble polymer emulsion (A- 1)obtained in Synthetic example 1, a mixture of 60 g of LIGHT-ACRYLATEHOA-HH (2-acryloyloxyethylhexahydropthalic acid manufactured by KyoeishaYushi Kagaku Kogyo Co., Ltd.), 20 g of LIGHT-ACRYLATE PO-A (phenoxyethylacrylate manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.), 20 g ofACRYESTER TMP (trimethylolpropane trimethacrylate manufactured byMitsubishi Rayon Co., Ltd.), 5 g of a photopolymerization initiator,Irgacure 907(2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-onemanufactured by Ciba-Geigy Corp.) and 5 g of Kayacure DETX(4-diethylthioxanthone manufactured by Nippon Kayaku Co., Ltd.) and 50 gof LMS-100 (talc manufactured by Fuji Talc Industrial Co., Ltd.) wereadded under stirring and emulsified. To the emulsion were mixed 80 g ofwater and 6 g of Blue-FLB conc. (a blue pigment dispersed in watermanufactured by Dainichiseika Colour & Chemicals Mfg. Co., Ltd.),yielding a photosensitive liquid (sample 2).

A photosensitized screen board was prepared as in Example II-1 by usingthis photosensitive liquid (sample II-2) and the printing test wasconducted. As the result, it was found that printing of 3000 piecesproduced good printed pieces with no failure of image and that a screenprinting stencil with excellent durability was obtained as with ExampleII-1.

Furthermore, the cured film was easily removed completely by spraying a3% aqueous sodium hydroxide solution at 45° C. at a spray pressure of 2kg/cm² to the screen printing stencil.

Example II-3

To 200 g of the photosensitive water-insoluble polymer emulsion (A-2)obtained in Synthetic Example 2, a mixture of 15 g of benzoin isobutylether, 75 g of pentaerythritol triacrylate and 75 g of Aronix M-8030(manufactured by Toagosei Co., Ltd.) and 50 g of LMS-100 (talcmanufactured by Fuji Talc Industrial Co., Ltd.) were added understirring and emulsified. To the emulsion were mixed 135 g of water and 6g of Blue-FLB conc. (a blue pigment dispersed in water manufactured byDainichiseika Colour & Chemicals Mfg. Co., Ltd.), yielding aphotosensitive liquid (sample II-3).

A photosensitized screen board was prepared as in Example II-1 by usingthis photosensitive liquid (sample II-3) and the printing test wasconducted. As the result, it was found that printing of 3000 piecesproduced good printed pieces with no failure of image and that a screenprinting stencil with excellent durability was obtained as with ExampleII-1.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Example II-4

To 200 g of the photosensitive water-insoluble polymer emulsion (A-2)obtained in Synthetic Example 2, 50 g of LIGHT-ACRYLATE HOA-HH(2-acryloyloxyethyhexahydropthalic acid manufactured by KyoeiSha YushiKagaku Kogyo Co., Ltd.), 50 g of ACRYESTER TMP (trimethylolpropanetrimethacrylate manufactured by Mitsubishi Rayon Co., Ltd.), 7 g of aphotopolymerization initiator, Irgacure 907(2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-onemanufactured by Ciba-Geigy Corp.) and 3 g of Kayacure DETX(4-diethylthioxanthone manufactured by Nippon Kayaku Co., Ltd.) wereadded under stirring and emulsified. To the emulsion were mixed 30 g ofwater and 6 g of a violet pigment dispersed in water (manufactured byDainichiseika Colour & Chemicals Mfg. Co., Ltd.), yielding aphotosensitive liquid (sample II-4).

From this photosensitive liquid (sample II-4), a photosensitized screenboard was prepared as in Example II-1 and the printing test wasconducted. As the result, it was found that printing of 3000 piecesproduced good printed pieces with no failure of image and that a screenprinting stencil with excellent durability was obtained as with ExampleII-1.

Furthermore, the cured film was easily removed completely by spraying a3% aqueous sodium hydroxide solution at 45° C. at a spray pressure of 2kg/cm² to the screen printing stencil.

Example II-5

A photosensitive film was prepared through three cycles of processcomprising applying the photosensitive liquid used in Example II-1((sample II-1), provided that Blue FBL was not incorporated therein) to70-mesh polyester mesh fabric (white) with a bucket for thick films anddrying it (hot-air drying at 30-40° C.). The screen photosensitive filmwas brought into contact with a mask film constituted of a circle 300 μmin diameter and then exposed to a 4 KW super-high pressure mercury lamp(manufactured by ORC Manufacturing Co., Ltd.) for 30 seconds at adistance of 1 m. The mask film was then removed, and subsequently theresulting specimen was immersed in water at 20° C. for 2 minutes,followed by washing with shower to remove the non-exposed portion. Bydrying thusly developed photosensitized board in the 45° C. hot air for15 minutes, a screen stencil was obtained. The thickness of the curedfilm formed on the board was 500 μm (excluding the thickness of thescreen). The resulting screen printing stencil had a pattern reproducedminutely. Using this stencil, a solder cream was printed on 1000 piecesof copper-laminated boards, producing good printed pieces with nofailure of image. This reveals that the screen printing stencil obtainedin this Example had excellent durability.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Example II-6

A screen printing board was prepared in a way of Example II-5 exceptusing the photosensitive liquid used in Example II-4 ((sample II-4),provided that the violet pigment dispersing in water was notincorporated therein.) The thickness of the cured film formed on theboard was 500 μm (excluding the thickness of the screen). The resultingscreen printing stencil had a pattern reproduced minutely. Using thisstencil, a solder cream was printed on 1000 pieces of copper-laminatedboards, producing good printed pieces with no failure of image. Thisreveals that the screen printing stencil obtained in this Example hadexcellent durability.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Example II-7

A photosensitive film was prepared through twenty cycles of processcomprising applying the photosensitive liquid used in Example II-1((sample II-1), provided that Blue FBL was not incorporated therein) to70-mesh polyester mesh fabric (white) with a bucket for thick films anddrying it (hot-air drying at 30-40° C.). The screen photosensitive filmwas brought into contact with a mask film constituted of a circle 500 μmin diameter and then exposed to a 4 KW super-high pressure mercury lamp(manufactured by ORC Manufacturing Co., Ltd.) for 120 seconds at adistance of 1 m. The mask film was then removed, and subsequently theresulting specimen was immersed in water at 20° C. for 2 minutes,followed by washing with shower to remove the non-exposed portion. Bydrying the thus developed photosensitized board in the 45° C. hot airfor 15 minutes, a screen stencil was obtained. The thickness of thecured film formed on the board was 2000 μm (excluding the thickness ofthe screen). The resulting screen printing stencil had a patternreproduced minutely. Using this stencil, a solder cream was printed on1000 pieces of copper-laminated boards, producing good printed pieceswith no failure of image. This reveals that the screen printing stencilobtained in this Example had excellent durability.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Example II-8

A screen printing board was prepared in a way of Example II-7 exceptusing the photosensitive liquid used in Example II-1 ((sample II-1),provided that the violet pigment dispersing in water was notincorporated therein.) The thickness of the cured film formed on theboard was 2000 μm (excluding the thickness of the screen). The resultingscreen printing stencil had a pattern reproduced minutely. Using thisstencil, a solder cream was printed on 1000 pieces of copper-laminatedboards, producing good printed pieces with no failure of image. Thisreveals that the screen printing stencil obtained in this Example hadexcellent durability.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Example II-9

A photosensitive liquid (sample II-9) was prepared in a way of ExampleII-1 except mixing the ingredients of the composition used in ExampleII-1 with the addition of 50 g of polyvinyl acetate emulsion HA- 10(manufactured by Clariant Polymers K.K.) Subsequently, a screen printingstencil with 150 μm wiring for printed wiring was obtained throughoperations the same as those in Example II-1.

Using this stencil, an etching resist ink (PLAS FINE PER-210Bmanufactured by Goo Chemical Co., Ltd.) was printed on 3000 pieces ofcopper-laminated boards, producing good printed pieces with no failureof image. This reveals that the screen printing stencil obtained in thisExample had excellent durability.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Example II-10

A photosensitive liquid (sample II-10) was prepared in a way of ExampleII-1 except mixing the ingredients of the composition used in ExampleII-1 with the addition of 50 g of a 15% aqueous solution (F-1) of theN-methylolacrylamide adduct of polyvinyl alcohol obtained in ReferenceProduction Example 1. Subsequently, a screen stencil with 150 μm wiringfor printed wiring was obtained through operations the same as those inExample II-1.

Using this stencil, an etching resist ink (PLAS FINE PER-210Bmanufactured by Goo Chemical Co., Ltd.) was printed on 3000 pieces ofcopper-laminated boards, producing good printed pieces with no failureof image. This reveals that the screen printing stencil obtained in thisExample had excellent durability.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Comparative Example II-1

To 200 g of (A- 1) obtained in Synthesis Example 1, 15 g of benzoinisobutyl ether was added under stirring and emulsified. To thisemulsion, 6 g of Blue FLB conc. (a blue pigment dispersed in watermanufactured by Dainichiseika Colour & Chemicals Mfg. Co., Ltd.),yielding a photosensitive liquid. Using this photosensitive liquid, ascreen photosensitized board was prepared in the same manner as ExampleII-1. The resulting screen printing stencil, however, was of poorresolution. The image formed, which should inherently be a straightline, staggered along the mesh of a screen. Moreover, 1000 pieces ofprints was made using this screen printing stencil, but a part of thecured film peeled.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Comparative Example II-2

Into a glass vessel equipped with a stirrer, 45 g of PVA-217 (polyvinylalcohol manufactured by Kuraray Co., Ltd., degree of polymerization:1700, degree of saponification: 88 mole %) and 255 g of ion-exchangewater were charged and dissolved on heating. To the solution, 150 g ofpentaerythritol triacrylate containing 7.5 g of benzoin isobutyl etherdissolved therein was added under stirring and emulsified. Furthermore,300 g of polyvinyl acetate emulsion HA-10 (Clariant Polymers K.K.) wasmixed and, subsequently, 3 g of a sulfate of a condensate ofp-diazodiphenylamine and p-formaldehyde (diazo resin) was mixed,yielding a photosensitive liquid.

Subsequently, a screen printing stencil was prepared in a way of ExampleII-5 except using the above photosensitive liquid as a photosensitiveliquid, changing the number of the repetitive application-drying step tofive times and changing the exposure time to 10 minutes. The thicknessof the cured film formed on the board was 500 μm (excluding thethickness of the screen). A solder cream was printed on copper-laminatedboards using this stencil, but when print had been put on 500 pieces, apart of the cured film removed and it became impossible to produceprinted products with good reproducibility.

Furthermore, the cured film was tried to remove by spraying a 3% aqueoussodium hydroxide solution at 45° C. at a spray pressure of 2 kg/cm² tothe screen printing stencil, but no removing occurred.

Comparative Example II-3

The production of a screen printing stencil with a cured film 2000 μm inthickness was attempted in a way of Example II-7 except changing thenumber of the repetitive application-drying step to 30 times andchanging the exposure time to 30 minutes from the condition adopted inComparative Example II-2. However, the cured film peeled off from thescreen mesh during the development and no image was obtained.

From the view of the above results, the photosensitive resin compositionof aqueous emulsion type obtained according to the present invention hashigh sensitivity. Moreover, since it can produce a cured filmparticularly excellent in water resistance and solvent resistance, itcan yield a screen printing stencil particularly excellent indurability. Furthermore, as is clear from Examples II-5 to II-8, thephotosensitive resin composition of aqueous emulsion type obtainedaccording to the present invention is excellent in developing property,resolution and durability and also has extremely higher exposuresensitivity in comparison with the conventional photosensitivecompositions for manufacturing screen printing stencils. Therefore, itcan easily produce a screen printing stencil with a thick film havingsuperior physical properties.

Moreover, when a compound (b) having at least one per molecule carboxylgroup and at least one per molecule photoreactive ethylenicallyunsaturated group is used as at least a part of ingredient (B), theresulting cured film becomes possible to be removed by dissolving with adilute aqueous alkaline solution or the like. Therefore, thephotosensitive resin composition of the present invention can be widelyused as various kinds of resist inks and as, for example, aphotosensitive resin composition for producing a dry film resist.

What is claimed is:
 1. A photosensitive resin composition in the form of an aqueous emulsion comprising: (A) an emulsion of a photosensitive water-insoluble polymer, the emulsion being obtained by reacting (i) an aqueous polymer emulsion which contains a water-insoluble polymer as its main component and which contains a polymer having a hydroxyl group with (ii) an N-alkylol(meth)acrylamide; (B) at least one monomer having at least one photoreactive ethylenically unsaturated group; (C) a photopolymerization initiator; and (E) an epoxy compound having at least two epoxy groups per molecule.
 2. A photosensitive resin composition in the form of an aqueous emulsion comprising: (A) an emulsion of a photosensitive water-insoluble polymer, the emulsion being obtained by reacting (i) an aqueous polymer emulsion which contains a water-insoluble polymer as its main component and which contains a polymer having a hydroxyl group with (ii) an N-alkylol(meth)acrylamide; (B) at least one monomer having at least one photoreactive ethylenically unsaturated group; and (C) a photopolymerization initiator, wherein the component (B) comprises a monomer (b) having at least one carboxyl group and at least one photoreactive ethylenically unsaturated group in a molecule.
 3. A method for producing a screen printing stencil comprising: (I) a step of providing a photosensitive resin composition according to claim 1 or 2; (II) a step of forming a film of the photosensitive resin composition on a releasable film; (III) a step of selectively exposing the film to form a cured film; (IV) a step of washing away to remove an non-exposed portion of the film; and (V) a step of transferring the resulting cured film onto a screen.
 4. A method for producing a printed wiring board produced by using the photosensitive resin composition according to claim 1 or 2 comprising: (I) a step of providing a substrate having a metallic layer formed on its surface; (II) a step of applying the photosensitive resin composition to the surface of the substrate and then drying it; (III) a step of selectively exposing a predetermined portion of the photosensitive resin composition which is applied to the substrate to form a cured film; (IV) a step of washing away to remove the non-exposed portion of the photosensitive resin composition; (V) a step of immersing the substrate in an etching solution to subject a part of the metallic layer to be etched; and (VI) a step of removing the cured film.
 5. A method for producing a printed wiring board produced by using the photosensitive resin composition according to claim 1 or 2 comprising: (I) a step of providing a substrate with a conductive circuit formed on its surface; (II) a step of applying the photosensitive resin composition to the surface of the substrate and then drying it; (III) a step of selectively exposing a predetermined portion of the photosensitive resin composition which is applied to the substrate to form a cured film; and (IV) a step of washing away to remove the non-exposed portion of the photosensitive resin composition.
 6. A method for producing a printed wiring board according to claim 5 further comprising a step of heating the cured film to obtain a permanent protective coating.
 7. A printed wiring board with a cured film on its surface, the cured film being made from the photosensitive resin composition according to claim 1 or
 2. 8. A printed wiring board according to claim 7 wherein the cured film is a permanent protective coating. 